This paper focuses on the third pillar of the Uruguay Round Agreement on Agriculture (URAA) of the World Trade Organization (WTO), the discipline of agricultural domestic support. The paper examines the current definition of agricultural domestic support used by the WTO, focusing on the Aggregate Measure of Support (AMS) and other forms of support that are less to least distorting (Blue and Green Box payments). The analysis looks at the recent experience of four member states (the United States, the European Union, Japan, and Brazil). The structure of recent support varies considerably by country. Some countries, notably the United States, have strategically used the de minimis exemption to deflate their support figures substantially in order to remain within AMS limits, even though total support has exceeded these limits. The paper investigates the possible effects of changing the definition of the AMS so that it better reflects current support conditioned by market forces. If market prices (world and/or domestic) were to be used to compute current market support, a greater variability of the AMS would result, and violations of AMS limits would be more likely given the anticyclical nature of policies included in the AMS, especially for the United States and European Union. We also identify possible changes that would lead to more substantial trade reforms. In particular, we argue for phasing out the de minimis exemption and Blue Box support, adding a generous Green Box definition, which would allow countries to move quickly away from trade-distorting policies (Amber Box and the most trade-distorting Blue Box policies), followed by a phase-down of Green Box payments over time. The recent reforms of the European Unionï¿½s Common Agricultural Policy (CAP) exemplify the spirit of the first part of the recommendation, while resistance to phase-down of Green Box payments may be overcome by a "reasonable" reduction schedule.